.container {
  margin: 0 auto;
}
/* 手机屏幕 小于768px */
@media screen and (max-width: 767px) {
  .container {
    width: 100%;
  }
}
/*小屏幕下  768px到到992px*/
@media screen and (min-width: 768px) {
  .container {
    width: 400px;
    border: 1px solid #ccc;
    margin-top: 40px;
  }
}

/*中屏幕下  992px到1200px*/
@media screen and (min-width: 992px) {
  .container {
    width: 400px;
    border: 1px solid #ccc;
    margin-top: 40px;
  }
}
/*大屏幕下 大于1170px*/
@media screen and (min-width: 1200px) {
  .container {
    width: 400px;
    border: 1px solid #ccc;
    margin-top: 40px;
    margin-bottom: 260px;
  }
}
